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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Interfaces híbridas de estireno sobre silício / Styrene hybrid interfaces in silicon

Francisco Nogueira Lima 26 April 2013 (has links)
Este trabalho trata do estudo teórico atomístico das conformações da molécula de estireno sobre a superfície de Si(100)(2xl):H. Estudamos a molécula fisissorvida e quimissorvida sobre esta superfície. Os cálculos foram realizados através de Dinâmica Molecular Clássica. Nós reparametrizamos o Universal Force Field (UFF) com base em cálculos ab initio para sistemas modelo, e comparação a dados experimentais. Nossos resultados indicam que no processo de fississorção a região de vale da superfície é preferencial, e ocorre formação de agregados de moléculas antes do contato com a superfície. Quando passamos à análise da quimissorção de uma molécula, a região de vale permanece sendo o sítio preferencial para a posição do grupo vinil. Para as conformações de linhas de estireno, a estrutura mais estável tem todas as moléculas dispostas sobre a região de vale (ordenamento tipo \"pilha-1r\"); identificamos também outra estrutura, quase degenerada em energia, na qual o grupo vinileno se dispõe em conformação tipo \"espinha de peixe\", alternando entre a região de vale e sobre o dímero. / In this work we present a theoretical study of ,the conformation of styrene molecules on the Si(100)(2xl):H surface. We studied the conformations for styrene molecules physisorbed and chemisorbed on this surface. The study was conducted by Classical Molecular Dynamics. We performed a re-parametrization of the Universal Force Field (UFF), based on ab initio calculations for model structures, and comparison to experimental data. Our results show that for the physisorbed situations, the styrene molecules preferentially interact with the surface valley. We also identified that the molecules aggregate in clusters before reaching the surface. The valley is again the region of lowest energy for the vinylene position, for chemisorption of a single styrene molecule on the monohydride surface. For systems where we have a styrene layer chemisorbed on the dimer row, the most stable structure has ali the molecules arranged on the valley region o f the surface ( 1r -stack); we find another structure, almost degenerate in energy, in which molecules arrange in a herringbone- like configuration, with the vinylene group alternating between the valley and dimer regions.
52

Functionalization and metallization of diamondoids / Fonctionnalisation et métallisation des diamantoïdes

Gunawan, Maria Agatha E. 21 May 2015 (has links)
Ces travaux de thèse développent des méthodes pour la synthèse de nouveaux organohybrides carbone-métal basés sur les diamantoïdes et le palladium.Les pressions de vapeur de divers diamantoïdes ont été mesurées grâce à un protocole original de mesures de l'état d'équilibre thermodynamique solide-vapeur. Leur relative volatilité a permis de réaliser des dépôts de diamontoïdes en phase vapeur, à diverses pressions (ambiante, vide primaire, et vide poussé) sur des substrats comme le silicium ou le mica. Les observations au MEB ont montré que, selon le type de groupes fonctionnels présents sur le diamantoïde, différentes formes cristallines peuvent être produites (tiges, aiguilles, triangles, formes octaédriques tronquées).L’OMCVD de palladium sur les diamantanes fonctionnalisés montre que le palladium se dépose préférentiellement sur le substrat du silicium plutôt que sur les cristaux de diamantoïdes portant des groupes hydroxy ou fluor. Nous avons alors envisagé la synthèse de nouveaux diamontoïdes portant des groupes phosphino, qui pourraient former une liaison covalente entre le diamontoïde modifié et le palladium.Un ensemble complet de diamondoïdes fonctionnalisés par des phosphines a été synthétisé. Certaines nouvelles phosphines primaires ont révélées une stabilité à l’air inattendue.Il a été montré que l’utilisation de phosphine P(III) comme sites d'ancrage a permis la formation du matériau hybride Pd@PH2-Diam-OH. Différents caractérisations (XPS, MEB, MET, et EDX) ont montré que le matériau Pd@PH2-Diam-OH formé est isolant, et présente des interactions Pd–P. / The thesis deals with development of synthetic methods for preparation of novel carbon-metal organohybrid based on diamondoid and palladium. The vapor pressure of various diamondoids was measured from a new measurement protocol at solid-vapor thermodynamic equilibrium state. Their volatile tendency opened a possibility to do deposition from gas phase and at various pressure (ambient, primary vacuum, and high vacuum) of diamondoids on silicon or mica substrates. SEM observations have shown that depending on the type of functional groups on the diamondoid, different crystal shapes can be produced (rods, needles, triangles, truncated octahedral form).OMCVD of palladium on functionalized diamantanes showed that Pd deposition occurs preferentially on the oxide native layer on silicon substrates than on diamondoid crystals bearing hydroxyl or fluorine groups. This urged the synthesis new diamondoids with phosphino groups in order to make strong covalent bonding between the modified diamondoid and palladium.A full set of functionalized diamondoid phosphines were synthesized with unexpected air-stability of some primary diamondoid phosphines were observedIt has been shown that the use of P(III) phosphine as anchoring sites allowed the formation of hybrid material Pd@PH2-Diam-OH. Different characterizations (XPS, SEM, TEM, and EDX) indicated that an insulator material Pd@PH2-Diam-OH formed during the CVD deposition with P–Pd interaction.
53

Conception et évaluation d'un pansement multicouche antibactérien pour le traitement des plaies chroniques / Conception and evaluation of an antibacterial dressing with multilayer system for the treatment of the chronic wounds

Aubert-Viard, François 26 September 2014 (has links)
Les plaies chroniques représentent un problème de santé publique dont la prévalence augmente avec l'âge, l'état de santé du patient et la sédentarité. En effet, 1,69% des personnes âgées de plus de 65 ans est atteint d'ulcères de la jambe dans les pays occidentaux. De plus, l'apparition de plaies chroniques augmente chez les patients atteints de diabète avec une probabilité de développer un ulcère du pied de 2,2%/an pour les patients diabétiques atteints de neuropathie (diabète de type I et II confondus). Le risque d'infection des plaies chroniques augmentant avec le temps de guérison de la plaie, il est donc nécessaire d'apporter des soins réguliers afin de prévenir ou lutter contre l'infection de ces plaies jusqu'à leur complète guérison. En cas d'infection, la colonisation critique ou infection localisée peut conduire, en cas d'absence de traitement adapté, à la nécessité d'une intervention chirurgicale afin de prévenir l'infection systémique voire la mort du patient. Cependant, la plaie chronique représente un site de colonisation favorable pour les agents pathogènes qui s'y développent rapidement. La prolifération des bactéries peut alors aboutir à la formation d'un biofilm protecteur diminuant l'efficacité des défenses de l'organisme et des agents antimicrobiens. L'objectif de ce travail de thèse est donc de concevoir un dispositif médical sous forme de pansement capable de libérer de façon prolongée un principe actif antibactérien à large spectre d'action. Le dispositif textile utilisé dans ce projet est un textile non-tissé à base de polyéthylène téréphtalate (PET) fonctionnalisé par le chitosane (CHT) par la méthode "Pad-Dry-Cure". La fonctionnalisation du CHT est réalisée par l'utilisation de deux agents réticulants, la génipine (Gpn) ou l'acide citrique (CTR), qui permet de créer un réseau de chitosane réticulé à la surface des fibres textiles. Le coating apporte ainsi des fonctions ioniques à la surface du PET; positives lorsque l’agent réticulant est la Gpn, positives ou négatives en fonction du ratio de CTR introduit dans la solution quand l’agent réticulant est le CTR.Les charges ioniques du support PET fonctionnalisé par le CHT réticulé par la Gpn (PET-Gpn/CHT) ont été utilisées pour la construction d'un système multicouche (MC) "Layer-by-Layer" auto-assemblé. Les polyélectrolytes (PE) utilisés pour la construction de ce MC par "Dip-Coating" sont le chitosan en tant que PE cationique et un polymère de cyclodextrine (CD) en tant que PE anionique, élaboré et étudié par le laboratoire lors de travaux précédents. La capacité de formation de complexe d'inclusion des CD, apportée par le polymère de CD incorporé au revêtement multicouche, a ensuite été utilisée afin de charger un antiseptique à large spectre d'action, la chlorhexidine (Chx). La construction du système MC a d'abord été optimisée puis une évaluation physico-chimique, biologique et microbiologique a été réalisée sur les textiles PET-Gpn/CHT recouvert d'un système MC chargé par la Chx. Une étude a aussi été menée sur le PET fonctionnalisé uniquement par le CHT réticulé par le CTR (PET-CTR/CHT). Ce système anionique ou cationique en fonction de la quantité d’agent réticulant introduite, a été chargé respectivement par l'argent (Ag+) ou l’'iode (I3-). Une évaluation physico-chimique et microbiologique a été réalisée sur ces supports textiles pour évaluer leur efficacité antibactérienne. Finalement un système multicouche a été construit sur le système PET-CTR anionique chargé d’argent afin de limiter sa libération hors du système MC. Ceci a été ensuite vérifié à travers une évaluation chimique complétée par des tests microbiologiques. / The chronic wounds represent a public health problem health which the prevalence increases with age, patient health and sedentary lifestyle. Indeed, in the occidental countries, 1.69% of the elderly person aged over 65 years is suffering from leg ulcers . Moreover, the chronic wounds appearance increases for the diabetic patients who suffering neuropathy (diabetic type I and II together) with 2.2%/years of probability to developp a leg ulcer. The infection of the chronic wounds increases with wound healing delay, thus, cares need to be repeated to prevent or fight wound infection until their complete healing. In the case of infected wound, the critical colonization or localized infection can result without adapted treatment to surgery operation in order to prevent systemic infection or death. Nevertheless, the chronic wound represents a favourable site for the rapid developpment of the pathogen agents. The bacterial proliferation can lead to the biofilm formation which increases the bacterial protection against the body\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'s natural defences and antimicrobial agents. So, the aim of this work is elaborate a medical device as wound dressing for extended broad spectrum antibacterial drug release. The textile device used in this project is a non-woven textile based on polyethylene terephtalate (PET) functionalized with Pad-Dry-Cure method with chitosan (CHT). In the present work, two crosslinking agents are evaluated, genipin (Gpn) and citric acid (CTR), which allows obtaining a CHT network coated at the surface of the textile fibers. Thus, there are ionic functions at the surface of the PET; positive charges when the crosslink agent is Gpn, positive or negative charges in function of the amount of the CTR used in the solution.The ionic charges from the PET functionalized by CHT crosslinked by Gpn (PET-Gpn/CHT), are used to build a multilayer system layer-by layer self-assembly. The polyelectrolytes (PE) used to build this multilayer system by dip-coating are: the CHT, as cationic PE, and cyclodextrin (CD) polymer, as anionic PE (it was developed and studied by the team in previously work). The ability of the CD to form inclusion complex, from the CD polymer included in the multilayer coating, is used in the case of PET-Gpn/CHT to load one antiseptic with broad spectrum, the chlorhexidine (Chx). This Chx loaded multilayer system is optimized and evaluated physic-chemically, biologically and microbiologically. The study is also realized on the functionalized PET-CTR/CHT. This system, anionic or cationic, in function of the quantity of the crosslinking agent used, is loaded respectively by silver (Ag+) or iodide (I3-). A physico-chemical and microbiological evaluation are realized to evaluate their antibacterial efficiency. Finally, the multilayer system is built-up on the anionic PET-CTR/CHT loaded by silver to reduce its release out of the multilayer system. Chemical completed by microbiology tests are realized to verify the influence on the antibacterial activity and the kinetic of the release of the multilayer system
54

Synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers and reaction chemistry of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at triosmium carbonyl clusters.

Poola, Bhaskar 12 1900 (has links)
Quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been synthesized as possible specific metal host systems. The synthesis and characterization of quinoxaline-functionalized, cage-annulated oxa- and thiacrown ethers have been described. The characterization of these host systems have been fully achieved in solution by using various techniques such as IR, 1H NMR, and 13C NMR spectroscopic methods, high-resolution mass spectrometry (HRMS), elemental microanalysis, and X-ray crystallographic analysis in case of one quinoxaline-functionalized, cage-annulated oxacrown ether compound. The synthesis of the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) is described. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligand bmi proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(bmi) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C(O)N(tolyl-p)C(O)]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(bmi) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(bmi), whose molecular structure has been determined by X-ray crystallography. The kinetics for the ligand isomerization have been investigated by UV-vis and 1H NMR spectroscopy in toluene solution over the temperature range of 318-348 K. On the basis of kinetic data conducted in the presence of added CO and the Eyring activation parameters, a non-dissociative phosphine migration across one of the Os-Os bonds is proposed. Orthometalation of one of the phenyl groups associated with the bmi ligand is triggered by near-UV photolysis of the chelating cluster 1,1- Os3(CO)10(bmi).
55

Enhancing UV-protection of clear coated wood by utilizing reactive UV-absorber and epoxyfunctionalized soybean oil

Olsson, Sara January 2012 (has links)
This work presents the development of a new pretreatment for clear coated wood, that aims to increase the photoprotection of exterior wood products, and at the same time make the system more environmentally friendly. The pretreatment comprises the reactive UV absorber 2-hydroxy-4(2,3-epoxy­propoxy)-benzophenone (HEPBP), which has a primary epoxy group that can be covalently attached to the hydroxyl groups of the wood substrate. This reactant is accompanied by renewable epoxy functionalized soybean oil (ESBO), which contains a secondary epoxy group that also has the ability to react with the substrate and that promotes the compatibility between the two reactants. The ESBO further seems to have the advantage of increasing the flexibility of the pretreated veneers as well as decreasing the amount of water in the cell wall of the wood. The study was performed in two parts where the first part focused solely on the development and performance of the pretreatment, whereas the second part used the knowledge gained from part one to evaluate the pretreatment in combination with an acrylic clear coating. Grafting reactions were performed on thin wood veneers heated in solvent. In the first part the reaction parameters, temperature and reaction time, were varied to study their effects on the final properties of the pretreatments. The veneers where then analyzed using FTIR to determine if grafting was achieved. Results show that grafting was successful for reactions performed at temperatures above 90 °C. For part two, grafting was successful for both the boil- and dip process, indicating that a considerably shorter reaction time can be used. Samples from both part one and two where then exposed to accelerated ageing and the color change was measured to estimate the UV-resistance. The first part showed improved UV-resistance for some of the pretreatments, whereas the second part was more difficult to evaluate due to the top coat, but a slight improvement can be seen for samples using the pretreatment. A positive result for part two is also that the pretreatment do not appear to affect the adhesion between the substrate and the top coat. It is hence concluded that the proposed pretreatment is a possible way of increasing the photostability of exterior wood. / Detta arbete beskriver utvecklandet av en ny förbehandling för klarlackat trä som syftar till att öka UV-beständigheten av träprodukter för utomhusbruk. Arbetet syftar även till att utveckla systemet till att bli miljövänligare än nuvarande liknande produkter på marknaden. Förbehandlingen utnyttjar primära epoxidgrupper hos den reaktiva UV-absorbenten 2-hydroxy-4(2,3-epoxy­propoxy)-bensofenon (HEPBP) för att skapa kovalenta bindningar till hydroxylgrupper hos träet. Den andra komponenten i systemet är förnyelsebar epoxiderad sojaolja (ESBO) innehållande sekundära epoxidgrupper som även dessa kan binda kovalent till träytan, samt gynna kompatibiliteten mellan de två reaktanterna. Oljan verkar dessutom öka flexibiliteten av förbehandlingen, samtidigt som den minskar mängden vatten som tränger in i cellväggen. Studien utfördes i två delar där den första delen fokuserade enbart på att utveckla förbehandlingen, medan den andra delen utnyttjade information från den första delen för att utvärdera funktionen av förbehandlingen i kombination med en akrylatbaserad klarlack. Ympningsreaktionerna utfördes på tunna träfaner i uppvärmd lösning. I första delen studerades hur temperatur- och reaktionstidsförändringar påverkar den slutgiltiga prestationen av förbehandlingen, och FTIR användes då för att verifiera ympningen. Resultaten visar att ympningen var lyckad för reaktioner utförda vid reaktionstemperaturer över 90 °C. För del två ansågs ympningen lyckad för både dopp- och kokreaktionen, vilket tyder på att betydligt kortare reaktionstider skulle kunna användas. Prover från både del ett och två utsattes sedan för accelererad åldring där färgförändringen av proverna mättes för att uppskatta UV-resistensen av behandlingarna. Första delen visade på ökad UV-beständighet för vissa av behandlingarna. Del två var dock svårare att utvärdera till följd av klarlacken, men en liten förbättring kan noteras för prover som är förbehandlade. En positiv notering från del två är även att adhesionen mellan klarlacken och träytan inte verkar ha påverkats av förbehandlingen. Med detta som grund dras slutsatsen att den föreslagna förbehandlingen kan förbättra UV-resistensen av klarlackat trä för utomhusbruk. / QC 20120330
56

Linearly-Annulated, Functionalized, β,β'-π-Extended Porphyrins

Moss, Austen Edmond 12 1900 (has links)
Benzannulation to porphyrin 2,3 positions has previously been accomplished using various methodologies in the past century, yet there remain limited methodologies to both annulate to the porphyrin periphery and add functional moieties that can then be derivatized for diverse applications. This dissertation describes the development of synthetic routes and characterization of a variety of linearly-annulated, functionalized, β,β'-π-extended porphyrins. There are five chapters in this dissertation, the first of which introduces synthesis and properties of porphyrins and π-extended porphyrins. Chapter 2 describes synthesis of pentacenequinone-fused and pentacene-fused poprhyrins with distinct and new optical absorbance properties. In chapter 3, synthesis and characterization of benzimidazole-fused porphyrins displaying external metal binding capability is described. The synthetic method developed in chapter 3 is extended in chapter 4 to synthesis of bisbenzimidazole-fused porphyrin dimers that show split Soret character, likely due to excitonic coupling between porphyrins of the dimer. Chapter 5 summarizes this dissertation and describes future directions that this dissertation provides foundation for.
57

Immobilization of Ethylene Bis-Indenyl Ligands on Functionalized Silica Gel

Simerly, Thomas, Milligan, Tyson, Mohseni, Ray, Vasiliev, Aleksey 26 September 2012 (has links)
Four ethylene bis-indenyl ligands containing tethers of various lengths were successfully immobilized on the surface of functionalized silica gel. The strategy of immobilization was based on catalytic thiol-ene coupling of terminal alkene groups in the tethers with surface thiol groups. Obtained materials have high BET surface area and pore volume. The method developed can be used for immobilization of catalytically active bis-indenyl metallocene complexes, thus preventing their dimerization and deactivation.
58

Tandem Transesterification in Polymer Synthesis: Gradient and Pinpoint‐Functionalized Polymers / タンデムエステル交換反応を基盤とした高分子合成:グラジエント・局所機能化ポリマー

Ogura, Yusuke 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20404号 / 工博第4341号 / 新制||工||1673(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 澤本 光男, 教授 中條 善樹, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
59

Structure-Property Relationships of N-Heterocycle Functionalized Triphenylphosphine Oxide-Based Poly (Arylene Ether)s

Meyer, Luke January 2018 (has links)
No description available.
60

Biophysics of Blood Membranes

Himbert, Sebastian 11 1900 (has links)
Red blood cells (RBCs) are the predominant cell type in blood and have a two-layered outer shell which is composed of a cytoskeleton network tethered to a cytoplasmic membrane. In this thesis, I study the structure and mechanical properties of the RBC’s cytoplasmic membrane (RBCcm) on the nanoscale and utilize this knowledge to functionalize this biological structure on a molecular level. In a first case study, I measure the membrane’s bending rigidity from thermal fluctuations observed in X-ray diffuse scattering (XDS) and Neutron Spin Echo (NSE) experiments, as well as Molecular Dynamics (MD) simulations. I provide evidence of the RBCcm's highly deformable nature with a bending rigidity that is substantially softer as compared to synthetic membranes. The methods are applied to RBCs that were stored for up to 5 weeks. I demonstrate that storage of RBCs leads to an increased fraction of liquid ordered membrane domains and an increased bending rigidity. RBCs are ideal for pharmaceutical applications as they provide access to numerous targets in the body, however lack specificity. Functionalizing the cytoplasmic membrane is thus a prerequisite to use these cells in biotechnology. I develop protocols throughout two studies to tune the membrane's lipid and protein composition. I investigate the impact of synthetic lipid molecules on the membrane's structure and demonstrate that small molecules can be encapsulated into liposomes that are formed from these hybrid membranes. Further, I provide direct evidence that the SARS-CoV 2 spike protein can be anchored into the RBCcm through a detergent mediated insertion protocol. These virus-like particles are observed to trigger seroconversion in mouse models, which demonstrates the potential of functionalized RBC in biotechnology. / Thesis / Doctor of Philosophy (PhD)

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